The invention relates to improvements in containers or cassettes (hereinafter called cassettes) for photosensitive materials. More particularly, the invention relates to improvements in cassettes for temporary storage of stacks of superimposed sheets of photosensitive material, such as X-ray film.
Cassettes of the type to which the present invention pertains can be utilized with advantage to supply sheets into, or to receive sheets from, apparatus or machines for the processing of photosensitive material. Reference may be had, for example, to German Pat. No. 31 22 582.
As a rule, a cassette for X-ray film must be introduced into a darkroom in order to receive a stack of superimposed films. The stack should not be higher than the depth of a chamber which is defined by a bottom wall and upstanding sidewalls of the cassette. If the stack in the cassette is too high, the uppermost sheet or sheets are likely to become misaligned in that they overlie the top surface or surfaces of one or more sidewalls. This can result in defacing of and/or other damage to the misaligned sheet or sheets when the cover of the cassette is moved to closed or sealing position in which the cover prevents penetration of light into the chamber for the stack of sheets of photosensitive material to thus permit removal of the loaded cassette from the darkroom.
A person who is in charge of manipulating cassettes and sheets of X-ray film in a darkroom, e.g., of inserting sheets into the chamber of a cassette, often encounters problems in attempting to properly insert the sheets in spite of illumination of the darkroom with customary red light (safelight). In other words, such person may or may not invariably detect the misalignment of one or more sheets at the top of a stack which fills or nearly fills the chamber of a cassette in the darkroom. Thus, the danger of defacing and/or otherwise damaging one or more sheets of a stack of such sheets in a freshly loaded cassette as a result of movement of the cover to its sealing position is always present.